Much of the energy used to power vehicles does not go towards moving the vehicle forward, but is instead dissipated to the surrounding environment. One area of energy loss is through the repeated deformation or radial flexure of the tires of the vehicle due to the weight of the vehicle. If the lost energy can be reclaimed, the recaptured energy may be used to propel the vehicle or be utilized to power auxiliary components.
Several methods have been proposed to recapture the lost energy from the deformation of vehicle tires. For example, one method as described in U.S. Pat. No. 4,061,200 to Thompson teaches using the output of a fluid motor to turn an electrical generator. A bellows pump assembly, which is mounted to vehicle's wheel rim and is compressed upon each revolution of the tire, pumps pressurized fluid that actuates the fluid motor. This system has the drawback associated with using fluid such as the potential for leaks, the use of valves which periodically fail, and the need to use fluids which maintain properties of compressibility and viscosity under extreme environmental conditions.
Another prior art approach to generating electric power is shown in U.S. Pat. No. 3,699,367 to Thomas, which uses a mechanical plunger actuated by the deforming tire to generate electrical power. One major disadvantage to this design is that a complex mechanical structure is requires which does not generate continuous electrical power. Further, the amount of power generated is not sufficient to recharge a battery.
Another approach to generating electrical power from tire deformation utilizes an iron core wrapped by a coil as described in U.S. Pat. No. 4,220,907 to Pappas. A magnet is normally in contact with one end of the core, but is pulled apart during deformation of the tire to create electromotive force within the coil. One drawback of this system involves the contact between the magnet and core which will cause wear and with repeated cycling, possibly leading to potential failure. Another disadvantage to this system design is that it is mechanically complex and only a small electromagnetic force will be produced. In addition, the system produces an asymmetrical voltage output.
Thus a simple, inexpensive system, which generates electricity on a continuous basis from tire deformation and which is mechanically simple, is desired.